Garmin has a program called spanner you can download from their site that takes the garmin usb input and converts it to nmea on a virtual serial port. It may work with the puck. I am using it with my gpsmap 76 and it interfaces with Maptech perfectly. Also with Microsoft streets and maps.
Good to know! I don't think I need the Garmin puck, however, as I can use more generic pucks (I don't have a Garmin plotter or anything else Garmin...no particular reason why...)